Retaining wall blocks are a great answer to erosion control, slope stabilization, and landscaping enhancement. You do not need to be professional to construct one. You can construct one yourself with the right tools, some planning, and minimal patience. This guidebook will walk you through step by step in simple and straightforward language.
What Is a Retaining Wall?
A retaining wall is a wall that is utilized to keep back soil or water. Homeowners use retaining walls to stop erosion of the soil, build garden beds, or grade a yard. Retaining wall blocks are stacking concrete blocks with interlocking pieces, so they are perfect for a do-it-yourself endeavor.
Materials and Tools You Will Need
Have the following materials and tools prior to your start:
Tools:
- Shovel
- Tape measure
- String and stakes
- Level
- Rubber mallet
- Hand tamper or plate compactor
- Circular saw with masonry blade (if needed)
Materials:
- Retaining wall blocks
- Crushed gravel (base)
- Paver sand (leveling)
- Landscape fabric
- Drain pipe (not necessary but necessary for walls over 2 feet tall)
- Backfill (gravel or clean dirt)
Step-by-Step Instructions to Install Retaining Wall Blocks
Step 1: Plan the Wall
Start with plotting where you’d like your wall to go. Use stakes and string to measure out the length. Spray paint the outline. Space the wall at least 2 feet from other buildings, fences, or trees.
Tips:
- Take a reading of the grade of the land.
- Decide how tall you want the wall to be.
- For walls above 3 feet, call in a professional.
Step 2: Dig the Trench
Dig a trench for your bottommost course of blocks. The trench has to be deep enough to cover at least 1/4 of the first block and have 6 inches of base of crushed gravel.
- Trench sizing chart:
- Depth = block height ÷ 4 + 6 inches (for the gravel)
- Width = block depth + 6 inches (to allow working space)
- Make the bottom of the trench level end to end.
Step 3: Gravel Base to Compact
Pour 4–6 inches of crushed gravel into the trench. Level it with a shovel or rake. Compact with a hand tamper or plate compactor.
A solid base keeps your wall stable and from shifting or settling down in the future.
Step 4: Level with Sand (Optional)
Some put a thin coat of leveling sand (approximately 1 inch) over the gravel. This provides fine adjustments before placing the first block. Level it and inspect the level frequently.
Step 5: Install the First Course of Blocks
This is the critical step. Your entire wall rests on this first row being level and straight.
Set the initial block on one end of the trench. Gently tap it in using a rubber mallet on the ground. Check it from top to bottom and side to side to get it exactly right. Use sand or gravel under it to tweak as needed.
Continue to stack the blocks one at a time down the trench. Check with the level after every block. Be patient. The leveler the first course, the less trouble the rest will be.
Step 6: Put in Drainage (If Necessary)
If your wall is over 2 feet high or is holding back heavy soil, you must put in a drain pipe behind the first course of blocks.
Place the pipe at the back of the blocks and set the pipe a bit so that water can pass through it. Gravel must cover it in a way that water can easily pass through it. It will prevent pressure from arising against the wall.
Step 7: Place the Second Row and Remaining Rows
After the first course is leveled and established, start establishing the second row. Stagger the blocks so that the seams won’t fall on top of each other. This is for stability.
Free clean the top of the first row to eliminate dust or other obstructions. Lock the next block tight against the previous block. Tap in place with mallet and ensure it’s level.
Repeat the same with every row. Keep checking that the wall is straight and level in the process.
Step 8: Backfill After Each Row
After every row, fill gravel or clean soil behind the wall blocks. This supports the wall and facilitates drainage.
Shrink the backfill prior to placing the next row of blocks. Don’t wait until the wall is complete before backfilling — do it row by row.
Step 9: Cap the Wall (Optional)
If you prefer to top the wall at a specific height, place cap blocks at the top. These give the wall a clean, finished look.
Spread construction adhesive on the top row, and install cap blocks. Hold firmly and let them dry according to adhesive directions.
Step 10: Complete and Clean Up
After everything is in place:
- Clear debris from the site.
- Backfill behind the wall with mulch or soil.
- Plant or install landscaping for a completed look.
Safety Reminders
- Cut or reposition blocks while wearing gloves and safety glasses.
- Don’t go 3–4 feet high without the help of a structural engineer.
- Make sure water can run away from the wall so that it doesn’t do any damage.
Common Errors to Avoid
- Not using the gravel base – Results in uneven settling.
- Not leveling the first row – Results in leaning or tilted walls.
- Poor drainage – Water will destroy your wall over time.
- Backfilling with loose soil – Backfilling with gravel or clean fill all the time.
Final Thoughts
Retaining wall block installation is a rewarding DIY project. Take the time and persistent effort, and you will have a strong and good-looking wall that will last you for many years. Start with a solid base, go slow to achieve the first row level, and drain and backfill properly. Take special care to pay attention to details, and your wall will be successful.
Whatever you’re employing a slope to contain, creating garden levels or just adding some pizzazz to your lawn, a block retaining wall is a smart and satisfying solution.
